A no-fly zone has been declared over the Wimbledon championships for the first
time since the September 11 terror attacks.

Aircraft are banned from flying below 500 feet over the All England Club in London SW19 and within a perimeter of 0.75 nautical miles.

Ground commander Supt Pete Dobson of the Metropolitan Police said that general security had been increased for this year's tournament, which ends just 18 days before the Olympics, and that more uniformed and plain clothed officers would be on the ground.

"I am conscious that the attention is on London throughout the whole summer," he said.

"I am acutely aware that if someone was to do something untoward here it could well have a knock on effect on the Olympics.There is a greater security awareness this year.

"We are always looking to improve security plans so we do review it and we do make some tactical changes so we can defeat anyone who is trying to do a hostile reconnaissance."

He said the exclusion zone had been enforced to "minimise disruption" after the club made complaints last year about the noise.

However, he admitted that although the decision had not been driven by security "it did help" particularly as the Olympic tennis matches will all be played at the club.

"We just don't want strange aircraft flying overhead if we can avoid it," he added.

The last time a no-fly zone was enforced at the tournament was for two consecutive years in the wake of the attacks on the World Trade Center in a direct response to the increased threat level.

Several individuals have also been banned from entering the site, many of whom are considered a particular threat to female players.

Their names have been circulated and they have been warned to keep away from the area for the duration of the next two weeks.

Supt Dobson declined to disclose how many were on the list but said: "There are a number of individuals of concern to women's tennis.

"Some are stalkers of players, some have been coaches that have been dismissed. There have been domestic issues within the tennis word and as a result they are not welcome at these events."

Security fears were heightened when Monica Seles was stabbed in the back with a nine-inch kitchen knife on court in April 1993. Her attacker, Gunter Parche, an obsessed Steffi Graf fan, was given a two-year suspended sentence.

Players such as Maria Sharapova and sisters Venus and Serena Williams are known to have been troubled by obsessive fans in the past while Martina Hingis once received a series of disturbing calls and faxes from a stalker.

A two-kilmometre dispersal zone is in force for the fifth year running which allows officers to move groups of two or more people deemed to be acting antisocially away from the area and to keep touts at bay.

Armed protection officers are also on site to assist VIP guests such as members of the Royal Family, government ministers and ambassadors.

Today, Princess Michael of Kent and Sir Clive Woodward will be among those in the Royal Box but fans will be keeping their eyes peeled for Pippa Middleton and her sister, the Duchess of Cambridge, who are both keen tennis fans and often visit the tournament.